The present invention relates to an automatic plate exchange/plate registration method and apparatus of a printing press, e.g., a rotary press, which reset a plate cylinder to an origin, perform automatic plate exchange, and thereafter return the plate cylinder to a position immediately before it is reset to the origin.
Recently, a printing press, e.g., a rotary press, employs an automatic plate exchange apparatus (e.g., refer to Japanese Patent Application No. 1-315381) for automatically exchanging a plate mounted on a plate cylinder.
In the automatic plate exchange apparatus of this type, the plate cylinder must be reset to a position (origin) optimum for exchange before automatic plate exchange is performed. That is, a separate plate registration control apparatus is used, and the plate cylinder is returned to the center (the center of the machine) of the possible operation range in the axial direction by operating a reset switch provided to the control apparatus.
When the plate cylinder is at the origin, the operation of the automatic plate exchange apparatus is started to exchange an old plate mounted on the plate cylinder with a new plate.
After the plate exchange operation is completed, the moving position of the plate cylinder in the axial direction is adjusted so that the center of the flow of the web coincides with the center of the right-and-left direction (axial direction of the plate cylinder) of the mounted new plate. To adjust the position of the plate cylinder, the plate registration control apparatus is used, and the motor is turned on/off by a switch operation while observing a numerical indicator provided to the control apparatus.
This operation will be described by way of a rotary press with reference to FIG. 4. A center .phi.a of a web 1 in the flowing direction does not necessarily coincide with a center .phi.b of the machine. That is, when the plate cylinder is at the origin, assume that the center in the right-and-left direction of a new plate 2 coincides with the center .phi.b of the machine. Due to the individual characteristics of the printing press and the like, a deviation .DELTA..phi. is caused between the center .phi.b of the new plate 2 in the right-and-left direction and the center .phi.a of the web in the flowing direction. The position of a plate cylinder 3 is adjusted in order to eliminate this deviation .DELTA..phi., i.e., to perform plate registration.
In the method described above, however, the operator must move around between the automatic plate exchange apparatus and the plate registration control apparatus. That is, the operator must operate the reset switch of the plate registration control apparatus, then start automatic plate exchange by the automatic plate exchange apparatus, and return to the plate registration control apparatus to adjust the position of the plate cylinder. This poses much load to the operator to degrade the operation efficiency.
Furthermore, it is cumbersome to adjust the position of the plate cylinder by the plate registration control apparatus, thus increasing the load to the operator and degradation in operation efficiency.